This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Mitosis is regulated at both global levels and local level. While global regulation drives mitotic progression, the localized regulation fine tunes mitosis by turning on and off various activities at specific times and locations. The chromosome passenger complex (CPC) is the best characterized mitotic regulator that operates at the local level. The localization of the CPC is dynamic throughout mitosis, which corresponds to its various mitotic activities. During premetaphase and metaphase the CPC localizes at inner centromere where it corrects misattachment of microtubule and kinetochore and generates spindle checkpoint signals. Little is known about how and where the CPC is targeted to the inner centromere. I propose to purify CPC from mitotic chromatin digested with MNase by LAP purification, an approach used to successfully identify novel kinetochore proteins and centromere proteins, combined with mass spectrometry and deep sequencing to address this question. Analysis of the function of the identified proteins and DNAs will lay a strong foundation to study CPC targeting as well as inner centromere assembly The long-term goals of this proposal are to understand how CPC movement is coupled to mitotic progression and how deregulation of such a process might contribute to tumorigenesis. Aurora-B kinase, the core of the CPC, has been found to be overexpressed in various types of tumors. In addition, a new class small molecules targeting to Aurora kinases have been proved to be promising anti-cancer drugs in early stage of clinical trials. However, cytotoxicity is an inevitable issue since these drugs inhibit the kinase activity which has a variety of mitotic functions. This issue might be overcome if we can find a way to inhibit a specific function of Aurora-B. Knowledge about CPC targeting might be an efficient and essential way to achieve such a goal.